Announced in a Reddit AMA today, Ubisoft confirmed that Assassin's Creed Odyssey will have a reversible cover, each side featuring a different playable character.
One side of the cover will represent Alexios, the male choice, while Kassandra, the female choice, is on the otherside. While it isn't said there which cover will be the default one, Ubisoft did confirm in a later answer that Kassandra is the canon story. They did emphasize, however, that there's no incorrect choice between the two.
If you want to learn more about Assassin's Creed Odyssey, check out New Gameplay Today playing through a good chunk of the new game, wrote down ten things to know about the game, and explain how the latest AC title is doubling down on Assassin's Creed Origins' RPG elements.